1. Field of the Invention
This invention relates to a method for the formation of aluminum conductive interconnections on an integrated circuit chip; and more particularly, to such method and apparatus wherein the number of required steps is substantially reduced.
2. Description of the Prior Art
In the formation of integrated circuit chips, the active elements are formed on and in a silicon wafer by diffusion, ion implant, and so forth, and the electrical interconnections between the various elements in the wafer can be formed by depositing aluminum over the respective chips and then anodizing the aluminum in a particular pattern to form the respective conductor circuits. In the anodization process, a barrier layer of aluminum oxide is formed over the aluminum and a photoresist pattern is then placed on the barrier layer. The barrier layer prevents the formation of hillocks in the aluminum during later processing. The barrier layer is then etched through the photoresist pattern and those portions of the aluminum layer thus exposed are then subsequently anodized to form insulating areas that define the conductive circuit patterns.
In prior art processes, the etchant employed to etch the barrier aluminum oxide layer was of such a nature as to cause deterioration of the photoresist pattern. Thus, the etching process had to be interrupted a number of times and the photoresist pattern again baked with each interruption and baking procedure taking extra amounts of time. Furthermore, after the barrier layer had been etched completely through, the wafer was then removed to a separate facility to anodize the exposed aluminum. The entire process required a number of handling steps, each one of which increased the chances of breakage of the wafer in addition to increasing the amount of time to prepare the conductive pattern.
It is, then, an object of the present invention to provide an improved process and apparatus for the etching and anodization of an aluminum conductive pattern on the surface of integrated circuit chip.
It is still another object of the present invention to provide an improved process and apparatus for the etching and anodization of an aluminum conductive pattern which does not require the interruption of the etching process and resulting loss of time.
It is still a further object of the present invention to provide an improved process and apparatus for the etching and anodization of an aluminum conductive pattern which requires a minimum number of handling steps and a reduced chance of breakage of the wafer being processed.